package udp_server;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpEchoServer {
    private DatagramSocket socket = null;

    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    //启动服务器
    public void start() throws IOException {
        System.out.println("服务器启动");
        while (true){
            //每次循环,就是处理一个请求响应
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096], 4096);
            socket.receive(requestPacket);
            String request = new String(requestPacket.getData(),0,requestPacket.getLength());
            String response = process(request);
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length
                    ,requestPacket.getSocketAddress());
            socket.send(responsePacket);

            //打印日志
            System.out.printf("[%s:%d] req: %s, resp: %s\n", requestPacket.getAddress().toString()
                    ,requestPacket.getPort(),request,response);
        }
    }

    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();
    }
}
